Machine for finishing gears



July 20, 1948. 1.. H. TURNER ETAL I 2,445,549

MACHINE FOR FINISHING GEARS Filed N v. e, 1945 1o Sheets-Sheet 1 FIG. I

INVENTOR. LYMAN H. TURNER OLIVER E BAUER By LEONARD c. MICHELSON July20, 1948. LIH. TURNER ETAL MACHINE FOR FINISHING GEARS 10 Sheets-Sheet 2Filed Nov. 6, 1945 FIG. 2 f

INVEN TOR. LYMAN H. TURNER OLIVER F. BAUER LEONARDF. MICHELSON July 20,1948. TURNER ET AL 2,445,649

MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 l0 Sheets-Sheet 3 INVENTOR. LYMAN H. TURNER 3 OLIVER F. BAUER y LEONARD c. MICHELSON Jul zo,194s. L."H. TURNER HAL 2,445,649

MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 6L0 Sheets-Sheet 4 FIG. 4

INVENTOR.

LYMAN H. TURNER OLIVER F. BAUER y LEONARD c. MICHEISON July 20, 1948.LI'H. TURNER El'AL 2,445,649

MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 10 Sheets-Sheet 5INVENTOR. LYMAN H. TURNER OLIVER F. BAUER By LEONARD c. MICHELSON July20, 1948. L. H. TURNER ETAL 2,445,649

' v MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 10 Sheets-Sheet 6FIG. 9

INVENTOR. (I) LYMAN H. TURNER OLIVER F. BAUER w By LEONARD c MICHELSONJuly 20, 1948.

L; H. TURNER ETAL MACHINE FOR FINISHING GEARS Filed NOV. 6, 1945 10Sheets-Sheet '7 I\ I, I

3 m I n Q g Q I q k O (\J N 0 INVENTOR. LYMAN H. TURNER OLIVER F BAUERLEONARD C. MICHELSON July 20, 1948. H. TURNER ETAL v MACHINE FORFINISHING GEARS Filed Nov. .6, 1945 01 8 1O Sheets-Sheet 8 INVENTOR.LYMAN H. TURNER ouvsn F. BAUER LEONARD C, MICHELSON Ju y 20, 194.8- 1.;H. TURNER ETAL 2,445,649

I MACHINE FOR FINISHING GEARS Filed Nov. 6, 1945 10 Sheets-Sheet 9 FIG.l3

FIG. l5

FIG-l6 FIG. I?

INVENTOR. LYMAN H. TURNER OLIVER F. BAUER y LEONARD c. MICHELSON July20, 1948. LI'H. TURNER EIAL 2,445,549

MACHINE FOR FINISHING GEARS Filed Nqv. 6, 1945 1o Sheets-Sheet 10 FIG.l8

IN VEN TOR. LYMAN H. TURNER OLIVER F. BAUER By LEONARD c. MICHELSONPatented July 20, 1948 UNITED STATES PATENT OFFICE MACHINE FOR FINISHINGGEARS Application November 8, 1945, Serial No. 827.024

19 Claims. 1

The present invention relates to machines for finishing gears, andparticularly to machines for lapping spiral bevel and hypoid gears.

In lapping bevel and hypoid gears, it is the practice to rotate thegears together in mesh under slight load while efiecting relativemotions between the gears lengthwise and traversely of their teeth andin the direction oi tooth depth. In the conventional type of lappingmachine, the gear or driven member of the gear pair, which is to belapped, is mounted on a spindle which is journaled in a quill, that ismounted in an oscillatory carrier for reciprocation in a direction axialof the spindle, and the carrier is mounted for oscillation about an axisparallel to but offset from the axis of the spindle. The lappingoperation is 'eflected by reciprocating the quill and oscillating thecarrier while the gear and pinion rotate together in mesh. Theoscillatory motion 01' the carrier causes the teeth of the driven gearto slide lengthwise over the teeth of the drive gear and itsimultaneously moves the gears relative to one another in a directiontransverse to the lengthwise sliding. The reciprocatory motion of thequill produces the relative movement of the gears in the direction oftooth depth and serves to maintain the backlash between the gearsconstant as the teeth slide lengthwise and transversely over oneanother. The gears are rotated together in one di-. rection for apredetermined period and then reversed. Then, after a predeterminedperiod of drive in the reverse direction, the machine is stopped.

Since opposite sides of the teeth of spiral bevel and hypoid gears arediiIerently curved, one side being longitudinally convex and the otherlongitudinally concave, it is usually desirable to employ differentrates and amounts of lapping motions during the rotation in oppositedirections of the gears being lapped. In the conventional lappingmachines, the rates of the oscillatory and reciprocator movements arecontrolled by two difierent sets of change gears, one set controllingthe rates of the motions during rotation in one direction of the gearsbein lapped and the other set controlling the rates of the motionsduring rotation of the gears in the opposite direction. The two sets ofchange gears are automatically shifted into and out of operativeposition at the time of reversal of the gears being lapped.

In the conventional machines, the position of the axis of the drivenspindle can be adjusted angularly about the axis of the carrier. Thispermits of varying the ratio of the lengthwise and transverse motions ofthe gears. Nevertheless,

2 a for a given angular position oi the spindle, the ratio of lengthwiseto transverse movement is fixed. Therefore, it is not possible to adjustthe amount of transverse motion independently oi the amount oflengthwise movement. Further than this, in the conventional machines,the oscillatory motions of the carrier and the reciprocatory movementsof the quill are controlled by cams, and, for lapping or burnishingdifferent pairs of gears, diflerent sets of cams must be used, each cambeing shaped to suit the job. Moreover, different parts of the cam,which controls the oscillatory motion, have to be used during theforward and reverse rotations of the gears, respectively, and in orderto have different amounts of oscillatory movements during forward andreverse rotations, the two parts of the cam have to have diflerentshapes.

The conventional machines, moreover, because of their structure, aresuitable only for lapping gears which mesh with axes at right angles.Heretofore no machine has been available for automatically lapping bevelor hypoid gears which mesh with axes at other than right angles, despitethe iact that such gears have been used in great numbers.

The primary objects of the present invention are to provide an automaticmachine for lappingspiral bevel and hypoid gears which will be moreconvenient to operate, cheaper in construction, easier to adjust fordifferent jobs and to change over from one job to another, and generallymore flexible in use and in range than any such machine previouslybuilt.

Another obiect of the invention is to provide an automatic machine forlapping spiral bevel and hypoid gears in which the need for special anddifferent cams for diiierent jobs is wholly eliminated, and in which asingle cam of simple shape may be employed for lapping any pair of gearswithin the range of the machine.

Another object of the invention is to provide an automatic machine forlapping spiral bevel and hypoid gears in which the same part of the camsurface is used for producing the oscillatory motions of the carrierduring both forward and reverse rotations of the gears, and thenecessity for differently shaped cam portions for controlling themovements during rotation of the gears in opposite directions isavoided.

A further object of the invention is to provide an automatic machine inwhich the times for lapping of the opposite sides of the teeth of a pairof gears can be adjusted at will and in which the character of thelapping action on opposite sides of the teeth can also be varied at willto suit the particular gears which are to be lapped.

Another object of the invention is to provide an automatic machine forlapping spiral bevel and hypoid gears in which the use of change gearsfor controlling the character 01' the finishing operation is eliminatedand in which quite simple con-J trols are employed instead for governingthe amounts of the several motions which together eitect the lappingoperation.

Still another object of the invention is to provide a lapping machine inwhich the several mothe carrier reciprocates and the angle through whichit oscillates for any amount of reciprocation or the head may be varied.Thus, the

tions for lapping are derived from a single cam Y and in which,therefore, the structure of the machine may be very much simplified.

A still further object of the invention is to provide a machine of thecharacter described in which simple, very eillcient means is providedfor applying a brake-load 01' any desired amount to the gears during thelapping operation,

Still another object or the invention is to provide a machine on whichall. types of spiral bevel and hypoid gears may be lapped regardless ofwhether they mesh with axes at acute, right, or obtuse angles.

Other objects of the invention will be apparent hereinafter from thespecification and from the recital of the appended claims. a

In the machine of the present invention, the lapping motions arepreferably applied to the pinion or drive member of the gear pair, whichis to be lapped, instead of as in the conventional design to the gear ordriven member. In the embodiment of the invention illustrated in thedrawings, the drive spindle is .ioumaled in a carrier that is mounted ina head for oscillation and reciprocation about and in the direction ofan axis oil'set from and parallel to the axis of the spindle, and thehead is mounted in a column or upright for reciprocation in a directionperpendicular to the axis of oscillation of the carrier. The axialreciprocation of the carrier eil'ects lengthwise sliding of the teeth ofone gear on the other; the oscillatory movement 01' the carrier variesthe depth of engagement of the gears as they move lengthwise; and thereciprocatory movement of the head effects transverse movement of thegears relative to one another.

All of the motions are derived from a single cam. This cam reciprccatesthe head; and the carrier is so connected to the relatively stationaryupright, on which the head slides, that as the head reciprocates it canboth oscillate and reciprocate the can'ier. There are two rollerssecured to the upright. One of these engages the straight guide surfaceof a block that is adjustable angularly about an axis extending at rightangles to the axis of the carrier. The other of these engages thestraight guide surface of a block that is adjustable angularly about anaxis is inclined to the direction of reciprocation of the lengthwise,transverse, and depthwise movements or the gears can be varied relativeto one another and the ratio of these movements can readily be changedto suit the requirements 01' any particular Job to be lapped.

The cam is oscillated to effect the reciprocation or the head. It may beprovided with an operative surface of progressively increasin radius sothat the greater the angle through which the cam is swung, the greaterthe distance through which the head is reciprocated. Adjustable stopscarried by a control member, that is mounted on the same shaft with thecam, determine the angle through which the cam swings.

. There is one set of stops provided for controlling the angle ctoscillation of the cam during forward rotation of the gears, that are tobe lapped, and there is a second set 01' stops provided 101' controllingthe angle of oscillation of the cam during reverse rotation of thegears. Since the angle of. oscillation of the cam determines the extentof the reciprocation of the head, and since the angles of adjustment ofthe guideblocks determine the extent oi! the oscillatory andreciprocatory movements of the carrier for a given amount of movement ofthe head, it will be obvious that a single cam can be used forcontrolling the extent of the motions of the machine for lapping anypair of gears within the range of the machine.

head, axial movement is imparted to the carrier as the roller rollsalong the straight guide surface of the block through reciprocation ofthe head. When the guide surface of the second block is inclined to thedirection of reciprocation of the head, swinging movement is imparted tothe carrier as the roller rolls along the straight guide surface of thesecond block in the reciprocation of the head. By adjusting the blocks,the angles of inclination of their guide surfaces to the direction ofreciprocation of the head may be varied. Thereby the distance throughwhich The rates of the motions are controlled electrically. Throughsuitable electrical controls, also,

them to be moved back and forth a plurality of' times during rotation ofthe gears in the reverse direction, and then stop the machine.

The mounting of the drive member on the head to which the lappingmotions are imparted, enables the gear or driven spindle to be mountedin a head which may be adjusted angularly to incline its axis at anydesired angle to the axis of the drive spindle, thereby permittingtapered gears that mesh with axes at right angles or at other thanright/ angles to be lapped without inordinately increasing the amount oifloor space required for the machine.

In the drawings:

Fig. 1 is a plan view of a machine built according to one embodiment ofthis invention;

Fig. 2 is an end view, partly in section, of the drive head of themachine and its supporting column;

Fig. 3 is a transverse vertical sectional view through the drive headtaken in a plane parallel to the view of Fig. 2 and on a somewhatenlarged scale, showing, also, a fragmentary section of the supportingcolumn;

Fig. 4 is a longitudinal vertical sectional view through. the. drivehead taken at right angles to the view of Fig. 3; I

Fig. 5 is a detail view showing one of the angularly adjustable blocksand rollers for controlling the oscillatory movement of the drive head;

Fig. 6 is a fragmentary view looking in the direction of the arrow 1 ofFig. 3, showing the cam,

which eiiects the lapping motions, and its folroller which. engages thisblock, the other roller,

and the supports for both rollers;

Fig. 7 is a fragmentary sectional view taken at right angles to the viewof Fig. 6;

Fig. 8 is an enlargedview looking at the right hand end of the cam driveshaft shown in Fig. 2 and showing the control member, adjustable stops,and limit switches which govern the amount of oscillation of the camshaft;

Fig. 9 is a fragmentary sectionalview showing the drive to the camshaft;

Fig. 10 is an elevational view, with parts broken away, of the drivenhead of the machine;

Fig. 11 is a vertical sectional view through the driven head and drivenspindle;

Figs. 12 to 17 inclusive are diagrammatic views illustrating therelative movements of the gear and pinion during lapping of a pair ofgears on a machine constructed according to this invention; and

Fig. 18 is an electrical wiring diagram of the machine.

Referring to the drawings by numerals of reference, 20 indicates the bedor frame of the machine. Mounted on the bed or frame for slidingadjustment on ways 21, which are formed on the upper face of the bed. isa plate 22. Mounted on the plate 22 for angular adjustment thereon aboutan axis a: is a swinging base 24. The swinging base is secured in anyadjusted position on the plate 22 by T-bolts 25 which engage in arouateT-slots 25 formed on the upper face of the plate 22 concentric of theaxis X. Mounted on the swinging base 24 for rectilinear adjustmentthereon along the ways 21, which are formed on the upper face of theswinging base, is the gear or driven head 28 of the machine. Adjustmentof the head 28 on the base 21 may be effected by rotation of the shaft45 (Fig. 10) which is journaled in the head. This shaft has a bevel gear45 secured to its lower end that meshes with a bevel gear 41.screw-shaft 48 that is journaled in the head and that threads into a nut49 that is fastened by bolts 52 to the sliding base 24. A graduated dial56 with a knurled knob that is secured to upper end of shaft 45 permitsthe adjustment to be made precisely. The head 28 can be secured in anyadjusted position on the sliding base by manipulation of the lever 43which operates a suitable clamping device (not shown).

Mounted on the bed 20 for rectilinear adjustment thereon in a directionat right angles to the direction of adjustment of the plate 22 on thebase is a column or upright 3|) which is adapted to slide in itsadjustment on the ways 3| (Fig. 1) that are formed on the upper face ofthe bed. The adjustment is effected by rotation of the handwheel 29which is secured to a screw-shaft (not shown) that is journaled in thebed and that threads into a nut (not shown) which is secured to thecolumn 30. The column can be secured in any adjusted position on theways 3i by manipulation of lever 53 (Fig. 2) whichserves to clamp thegib 54 against the underside of one of the ways 3|.

Mounted on the column 39 for vertical adjustment thereon is the drivehead 32 of the machine. The adjustment of the drive head is effected byrotation of the screw shaft 34 (Fig. 3). This shaft is rotatably mountedin the column 39 on anti-friction bearings 35 and threads into a nut 35that is secured in a plate 31. The plate 31 has a guide portion ofdove-tailed shape, as shown in Fig. '1, which is adapted to fit into andThis bevel gear is secured to a.

slide in a correspondingly shaped guide slot formed in the column 35. Atapered gib 55 and screw 55 serve to take up wear between the dovetailedguide portion and its way.

The drive head 32 is guided in its adjustment on the column 35 by theL-shaped ways 35 (Fig. 1). For the purpose of reducing friction to aminimum and of making this adjustment as smooth as possible, there aretwo sets of rollers mounted in the drive head 32 to engage and roll onthe two ways 55 as the head is adjusted on the column. In each set ofrollers, there is an upper and a lower roller 39 (Fig. 2) which engagethe front face of a guide way 38, an upper and lower roller 40 whichengage the rear face of the guide way, and an upper and lower roller 4|which engage one side face of the guideway, see 'Fig. 1. The adjustmentof the head 32 on the column 30 may be made precisely throughuse of theknurled knob and graduated dial 42 which is secured to thescrew shaft34. The several rollers 39, 45, and 4| are rotatably mounted on studs,such as the stud 44 shown in Fig. 4, which are secured m the head 32.

The mountings and adjustments of the heads 28 and 32 on the bed 20 ofthe machine are similar to those of the heads in the gear testingmachine of the United States patent of Oliver F. Bauer, No. 1,909,088,issued May 16, 1933.

Mounted in the head 32 for oscillatory and reciprocatory movementtherein is a carrier 59 (Figs. 2, 3, and 4). This carrier is mounted ona rod or bar 5| which is secured at its opposite ends in the drive head32. The carrier is mounted on this bar by means of the sleeve bearings53 and 54 so that it may not only swing about the bar but also havelimited sliding movement to and fro along the bar. The bar has anenlarged head at one end which holds it against movement in the drivehead 32 in one direction, and the nut 55, which is threaded to the bar,serves to hold the bar against movement relative to the drive head inthe opposite direction.

Journaled in the carrier with its axis offset from but parallel to thebar 5| is the drive spindle 51 of the machine. This spindle is mountedin the carrier on anti-friction bearings 58 and 59. A labyrinth seal 59is secured to the carrier at one end of the spindle 51 to prevent entryof dirt or grit into the bearings 59, while the bearing 58 is protectedby the front wall of a cylinder 51, which is shown only .fragmentarilyin Fig. 4, and which is secured to the opposite end of the carrier byscrews 53.

The pinion or drive member P (Fig. 1) of the gear pair, which is to belapped, is adapted to be secured to the drive spindle 51 by any suitablemeans as, for instance, by a clamp and draw bar (not shown). Thecylinder 6| may form part of a conventional hydraulic chucking mechanismfor securing the pinion to the spindle 51.

During operation of the machine, the drive spindle 51 is adapted to bedriven first in one direction and then in the other from the motor 65.This motor is secured to the column 30 and drives the spindle 51 througha belt (not shown) and the pulley 55, the latter being keyed to thespindle 51.

During operation of the machine, also, the head 32 is moved up and downon the column 30. ,The reciprocatory movement of the head 32 is effectedthrough operation of a motor 10 which is indicated diagrammatically inFig. 18. This motor drives a shaft 1| (Fig. 9) which is Journaled onanti-friction bearings 12 and 13 in the column 30.

v7 I This shaft h'as-a worm (not shown) secured to or integral with itthat meshes with a worm wheel '14 which is keyed to a shaft 18. Theshaft 18 is journaled in the column 38 on anti-friction bearings 11 and18 and has a worm 18 integral with it that meshes with a worm wheel 88(Figs. 9 and 2) that is keyed to a shaft III. The shaft II is journaledin any suitable manner in the column 38 and is connected throughuniversal joints and a stub shaft 83 with a shaft 84 (Figs. 2 and 3)that is suitably journaled in the plate 31.

Secured to the inner end of the shaft 84 is the cam 85 (Figs. 2, 3, and6). A roller 88 rides on the periphery of this cam. \This roller isrotatably mounted upon a stud 81 that is secured to the head 32 byscrews 88. The cam 85 may be formed as shown in Fig. 6, so that itsperipheral surface is at a progressively varying distance from the axisof the shaft 84. Hence, as the shaft swings, the head 82 rises or fallsdepending upon the direction of movement of the shaft.

Pivotally mounted upon a pin 88 that projects forwardly from the plate81 through a slot 88 in the head 32 (Figs. 6 and 7) is a link 8i. Thislink is pivotally connected by means of a pin 82 to a lever 84. Thelever 84 is pivotally mounted at one end upon a pin 88 that is securedin a bracket 88. This bracket is fastened by means of screws 81 to thework head 32. The lever 84 carries a pin 88 at its free end. Upon thispin is rotatably mounted a roller 88 (Figs. 3, 6, and 7). The roller 89is adapted to engage a straight slabbed-oif guide surface I88 formed ona block I 8 i This block is integral with a shaft I82 which is mountedin the carrier 58 for rotatable adjustment therein. The axis of thisshaft extends at right angles to the axis of the spindle 51.

The angle of adjustment of the block I8I determines the amount of axialmovement imparted to the drive spindle 51, that is, the amount ofrelative lengthwise movement between the teeth of the pinion P and theteeth of the mating gear G (Fig. 1), for as the drive head 32 rises andfalls under actuation of the cam 85, the roller 88 will ride up and downon the guide surface I88 of the block ii. If this guide surface isvertical,

'that is, is parallel to the direction of movement of the head 32, noaxial movement will be imparted to the spindle 51 and the carrier 58. Ifthe guide surface I88 is inclined to the vertical, however. the carrier58 and, with it, the spindle 51 will move back and forth as the workhead rises and falls.

The amount of the back and forth movement will depend upon the angle ofadjustment of the block I8l. Moreover, the direction of adjustment ofthe block angularly one side or other of the vertical will determine thedirection of movement of the carrier and spindle for rise and fall ofthe head 32. Thus, for one angular p sition of the block IN, the carrierand work spindle will move inwardly as the head rises, while when theblock is adjusted to the opposite angle, the carrier .and work spindlewill move outwardly as the drive head rises. This permits of lappinggears whether the pinion is chucked in the usual fashion on the drivespindle with its apex extending forward of the spindle or is chuckedbackward with its apex extending toward the rear of the spindle. Theangular position of the block I8I may be adjusted precisely through useof the micrometer dial I83 which is secured to the shaft I82 (Fig. 3).

A spring-pressed plunger I85 (Figs, 3 and 4), which is housed in thehead 32, serves to constantly urge the carrier 58 and spindle 51 towardrearward position. This plunger which is actuated by the spring I88engages one end of a lever I81 that is pivotally mounted at its oppositeend by means of the pin I88 in the head 32. .The lever carries a pin I88between its ends on which is mounted a roller I I8 that is adapted toengage a hardened block III which is secured in the carrier 58.

Fastened to the plate 31 by means of screws III is a bracket II8 (Figs.3, 4, and 6). Journaled on anti-friction bearings H1 in this bracket isa cylinder H8 which is formed at opposite ends with roller portions H8and I28. These rollers are adapted to engage, respectively, thestraightsided projecting portions I2I and I22 of blocks I23 and I24,respectively. These blocks are mounted on arms 5 and I28, respectively.which are integral with and project from the carrier 58. The blocks areadjustable angularLv about aligned-axes which extend parallel to theaxis of the drive spindle 51, and they may be adjusted angularly toincline the straight surfaces I2I and I22 at any desired angle to thevertical. Thereby the amount of swing oi the carrier 58 about the axisof shaft 5i may be adjusted to adjust the amount of depthwise in-and-outmovement of the pinion P as the head 32 rises and falls under actuationof the cam 85. It will be obvious that if the blocks I23 and I24 areadjusted so that the surfaces I2I and I22 are vertical. then no swingingmovement will be imparted to the carrier 58 about the bar 5I as the head32 rises and falls, but if the surfaces I2I and I22 are inclined to thevertical, then as the head 32 rises and falls, the carrier will beoscillated about the axis of bar 5i and in-and-out depthwise movementwill be imparted to the pinion. The direction of this movement for therise of the head can be determined by the setting the guide surfaces I2Iand I22 one side or other of the vertical. For precisely adjusting theseguide surfaces, the blocks I23 and I24 are graduated as shown in Fig. 4to read against zero index pointers carried by the arms I25 and I28,respectively.

For holding the guide surfaces I2I and I22 against the rollers H8 andI28, respectively, two spring-pressed plungers I3I and I32 (Fig. 3) areprovided. These are housed in the head 32. The plunger I3I operatesagainst a roller I33 which is rotatably mounted on a stud I35 that issecured in. one side of the carrier 58. The plunger I32 operates againstthe roller I34 that is rotatably mounted on a stud I38 that is securedin the opposite side of the carrier 58. The spring I 31, which actuatesthe plunger I3I, is more powerful than the spring, which actuates theplunger I32, and will ordinarily overcome the action of the latterspring.

When the blocks I23 and I 24 are in the positions shown in Fig. 4, thespring I31 overcomes the spring of the smaller plunger I32 and tends toholdthe guide surfaces I2! and I22 of the blocks against the rollers H9and I28. When the blocks are reversed, however, the plunger I3I islocked down by rotating the lock-screw I38 which has a lock-pin I38formed eccentrically on its inner end that engages in a recess I48 inone side of the plunger. Then the smaller plunger I32 is operable tourge the carrier 58 in the ,opposite direction to hold the guidesurfaces I2I and I 22 against the rollers H9 and l28 The amount of theupand-down movement of the drive head 32 is governed from a controlmember I48 (Figs. 2-and 8) which is secured to the shaft 8 I. There aretwo pairs of stop plates secured to the rear face of the control memberI40. The two members of one pair are denotedat IM and I42, respectively,while the two members of the other pair are designated at I43 and 144,respectively. Each of these members is adustable angularly about theaxis of the shaft 8| and may be fastened in any adjusted position on therear face of the control member I40 by a T-bolt I45 whose head engagesin a circular T- slot I46 that is formed in the rear face of the memberI40. The stop plates are locked in position by tightening the knurlednuts I46 which thread onto the T-bolts.

The stop plates have stop buttons I41, I48, I49, and I50, respectively,formed on their peripheral surfaces. The rear face of the control memberis suitably graduated, as clearly shown in Fig. 8, to read against zeromarks on the stop plates so that each pair of stop plates can beadjusted to space the stop buttons of that pair the desired distanceapart.

The stop buttons I41 and I48 are adapted, during oscillation of theshaft 6|, to rock a lever I56 that is pivotally mounted by means of thestud Pivotal movement of the lever in this direction is limited by anadjustable stop I59 which is also carried by bracket I62. As the leverrocks about its pivot I51, it pushes in the plunger I60 to close thelimit switch I6I. This limit switch is also carried by the bracket I62.

The buttons I49 and I50 are adapted to engage the nose I65 of a leverI68 which is pivoted by the stud I61 in the column 30. The lever I66 isconstantly urged inwardly about its pivot pin I61 by a spring-pressedplunger I68 that is carried by a bracket I12 which is secured to thecolumn 30. An adjustable stop-pin I69, which is also carried by" thebracket I12, serves to limit the inward movement of the lever I66. Asthe lever is rocked about its pivot against the resistance of thespringpressed plunger I68 by engagement of one of the stop buttons I49or I50 with the lug I65, the lever presses the plunger I10 of the limitswitch I" inwardly to trip the limit switch. This limit switch is alsocarried by bracket I12.

The machine shown is wired, as will be described more particularlyhereinafter, so that the shaft 8| and control member I40 are oscillatedback and forth, being driven first in one direction and then in theother, the direction of rotation being reversed by tripping the limitswitches I6I and "I. When the machine is started up, the limit switchI6I controls the direction of rotation of the control member I40 andshaft 8|, and each time that one or other of the buttons I41 or I48strikes the nose I55 of the lever I56, the control member and shaft arereversed. Thus, at this stage of the operation, the amount ofoscillation of shaft 8|, that is, the amount of movement of drive head32, is controlled by the distance that stop-buttons I41 and I48 are setapart.

The machine illustrated is further so wired that after two completeoscillations of the shaft, the limit switch I6I is rendered inoperativeand the limit switch I1I becomes operative. Then the oscillations of theshaft and control member are controlled by the stop buttons I49 and I50.Each time that one of these stop-buttons contacts the nose I65 of leverI66, the direction of rotation of the shaft M is reversed, and theamount of swing of shaft 8| and of movement of drive head 32 iscontrolled at this stage of the operation by the distance that buttonsI49 and I50 are set apart. The machine illustrated is so wired furtherthat after two complete oscillations of the shaft under control ofbuttons I 49 and I50, the limit switch I1I is rendered inoperative andthemachine is stopped.

Safety stops are provided to stop the machine in case the stop-buttonsI41 and I48 or I49 and I50 fail to function and fail to reverse thedirection of rotation of the shaft. These safety devices are in the formof additional stop-buttons I13 and I14 which are provided on theperiphery of the control member I40. These stop-buttons I13 and I14 areplaced-diametrically opposite from one another, one between the stopplates HI and I43, and the other between the stop plates I42 and I44.These buttons I13 and I14 are adapted to engage with the V-shaped noseof a lever I18 (Fig. 2) which is pivotally mounted alongside the leverI66 on the stud I61. The lever I18 is constantly'urged toward theperiphery of the control member I40 by a spring-pressed plunger similarto the plunger I68 and its movement may be limited in one directionthrough an adjustable stop pin similar to the stop pin I69. The leverI18 is adapted to actuate, when rocked, the limit switch I80, which iscarried by the bracket I12. This limit switch is wired to stop themachine, when tripped, as will be described more particularlyhereinafter.

Mounted on the periphery of the control member I40 at an angularposition between the buttons I41 and I48 (see Fig.8) but in a positiondisplaced axially from buttons I41 and I48 so as to clear the nose I55of lever I56 is a button I82. This button is adapted to engage thetapered nose I15 of a lever I11 (Fig. 2) which is mounted alongsidelever I56 to pivot about stud I51. The lever I11; when rocked, isadapted to trip a limit switch I19. On each swing of control member I40,whether under control of stop-buttons I41 and I48 or of stop-buttons I49and I50, then, limit switch I19 will be tripped. The purpose of thislimit switch will appear hereinafter.

The gear G, or driven member of the pair, which is to be lapped, ismounted on the spindle I (Figs. 10 and 11). This spindle is rotatablymounted in the driven head 28 of the machine on suitable anti-frictionbearings 200 and 2M. The gear G may be secured to this spindle by anysuitable means, for instance, by a draw bar I86 and a clamping disc (notshown). The draw bar is secured to a sleeve- I81 through the nuts I88and a nipple I69, the latter threading into the sleeve. The draw bar isconstantly urged toward workclamping position by a coil spring I90 whichsurrounds the sleeve I81 and which is interposed between the head of thesleeve and a nipple I84 that is keyed to spindle I85. The draw-bar isadapted to be moved to work-releasing position through application offluid pressure to the rear end of a piston I83, which is housed within acylinder I9I that is secured to head'28. Fluid under pressure menace 1which it is desired to lap away, very simple means have been providedfor taking up'the backlash and exerting-a moderate pressure be tween thegears throughout the whole lapping operation. For these purposes, agenerator 205 is mounted in the driven head 28 to be driven from thedriven spindle 135 through the pulleys 225 and 25V and the connectingbelt 208. A rheostatiiid (Fi 18) of any suitable construction isprovided for varying the resistance of the generator to adjust the brakeload on the gears.

The machine of this invention, like the machine of the Bauer patentabove mentioned, may he used for testing gears. ing gears, the variousoscillating and reciprocatins motions of head 52 and carrier 52 are notemployed, but the gears are simply run together under load. For applyinga load to the gears during testing. a standard hand brake may beemployed which may, as illustrated in Fig. 10, he in the term of a pairof brake-shoes 212 and tilt that are pivoted on the shaft 2 to engageWhen used for testl2 13in the positions which they occupy when themachine is stopped.

To put the machine in operation, the operator pushes in thenormally-open start-button 255.

' arm 284 of the relay 252, the line 235, the coil 2%, and the line 255to the main line In. When the coil 280 of controller 235 is energized,the

switch-arms 250, 2%, and 232 of the controller 235 are closed, thusclosing the circuit to the main motor 55 from the main lines L1, Lo, andLa through the lines 253,294, and 295 and starting this motor.

the periphery of a brake-drum 215 that is se-- cured to the spindle 185.The brake-shoes are constantly urged toward released position bycoil-springs 2 I and 211. These springs surround the pin 218 and areinterposed between the free ends of the brake-shoesand opposite faces of9. lug .2l3 which is integral with or secured to the head 25. Thehand-brake is adapted to be actuated by a hand lever 220 which is keyedto a shaft 221 that is iournaled in the head 28'. Keyed to the shaft221, also, is a bell-crank 223. One arm of this bell crank is connectedthrough a link 224 with an actuating member 225 that engages one of thebrake shoes 212. The other arm of the bell-crank is engaged by a coilspring 225. This spring is interposed between this arm of the bell-crankand a lug 221 formed on a bracket 220' that is integral with or securedto the head 23. spring 225 serves to counterbalance lever 220. Bypressing down on the lever be used advantageously not only in testingbut also in lapping if a considerable amount of stock is required to beremoved in lapping.

One way in which the machine may be wired to accomplish the purposes ofthe present invention is illustrated diagrammatically in Fig. 18. Here235 denotes the controller for the main motor 55: 235 and 231 designatecombination armature-field rheostats for controlling the speed ofrotation of the oscillating motor during rotation in opposite directionsof the gears that are to be lapped; 233 denotes an A. C.-D. C. rectiherfor the field 233 of the oscillating motor 240 denotes an A. C.-D. C.rectifier for the armature 2 of the oscillating motor iii; 242desighates an A. C.-D. C. rectifier for the generator 255; 243 the shuntfield of the generator 205; 244 the armature of the generator; and 245the load resistor for the generator. The motors 65 and I0, and thegenerator 205 may be of standard construction. The parts 235, 236, 235,240, 231, 242, 210 and 245 may also be standard parts of any suitablestructure. The machine is provided with a plurality of relays 250, 2:,252, 253, and 254. The relay 254 is a ratchet relay. All

of these relays may be of any standard or suitable structure. Themachine is also provided with standard start and stop-buttons 255 and251, respectively. The parts are shown in Fig.

When the starting button is closed, the oscillating motor is alsostarted. This is aifected by energizing the coil 300 of the controller245. The circuit to the coil 300 is-made from the main line L]. throughtthe lines 250 and 251, the limit switch I30, the line 252, thestop-button 251, the line 253, the start button 255, the lines 254, "I,and 302, the switch arm 303 of the relay 251, the line 304, the coil 300and the lines 355 and 215 to the main line L2. The energizing oi thecoil 500 closes the switch arms 305 and 301 of the controller 245 makinga circuit to the armature 241 of the oscillating motor from the mainline Li through the lines 3i0and 311, the rectifier 240, the line 3i2,switch arm 305, line 313, the armature 2", the line 314,-the switch arm301, the line M5, the rectifier 240 and the lines 315 and 210 to themain line L2. The circuit to. the shunt field 239 of the oscillatingmotor 10 is always closed, when the machine is in operation, from themain line L1 through the lines 3l0 and 311, the rectifier 238, the line315, the shunt winding 233, the line 3l3, the rectifier 235, and thelines 320 and 210 to the mainline 12. Thus,

- the motor 10 is started.

When the start button 255 is closed, a circuit is also closed from themain line L1 through thelines 250 and 251, the normally-closed limitswitch 150 (Figs. 8 and 2) the line 252, the normally-closed stop button251, the line 253, the start button 255, the line 254, the movableswitch arm 255 of the ratchet relay 254 and the number one station ofthis relay, the line. 255, the coil 251 i511, line 252, stop-button 251,line 253, start-button 255, lines 254 and 214, switch-arm 2" of relay253, line 215, coll 215 of relay 255, and lines 259 and 210 to main lineL2, thus energizing the coil 215 of the relay 250, closing theswitch-arm 211 and opening the switch arm 215 of this relay.

With the main motor 55 running, the gears P and G, which are to belapped, rotate in engagement, and with the oscillating motor 10 running,the shaft 8| and cam 55 are oscillated to move the head 32, to swing andreciprocate the carrier 50. As the shaft 5| swings in one direction fromstarting position, the button 152 (Fig. 8) may strike the nose of thelever 111 (Fig; 2), closing the limit switch I13, (Figs. 2 and 18). Atthis stage, however, the closing of limit switch I18 does not effect anyaction. As the shaft 8! swings on, though, the button I41 striks thenose I58 of the lever I56, closing the limit switch I6I. This energizesthe coil 325 of the ratchet-relay 254, the circuit to this coil beingmade from the main line L1 through the lines 260 and 326, the now-closedlimit switch I6! the line 321, the switch-arm 328 of relay 252, thelines 330 and 33!, the coil 325, and the lines 332 and 210 to the mainline L2. When the coil 325 is energized, the switch-arm 265 is advancedfrom station 1 to station 2 of the ratchet relay 254. v

The shift of the switch-arm 265 causes the coil 335 of the relay 25! tobe energized, the circuit to this coil being made from the main line L1through the lines 260 and 26!, the limit switch I80, line 262, the stopbutton 251, the lines 336 and 331, the now-closed switch-arm 211 of therelay 250, the lines 338 and 264, the switch-arm 265 of ratchet relay254, No. 2 station of that relay, the line 338, the coil 335, and thelines 343, I

266 and 210 to the main line La.

The energizing of the coil 335 causes the switch-arm 306 to be closedand the switch-arm 303 to be opened. The opening of the switcharm 303breaks the circuit to the coil 300 of the controller 246 and stops theforward rotation of the oscillating motor 10. The closing of the'switch-arm 306 makes a circuit to the coil 340 of this controller,causing the motor to be driven in reverse. The circuit to the coil 340is from the main line L1 through the lines 260 and 26!, the limit switchI80, the line 262, the stop-button 251, the lines 336 and 331, theswitcharm 211 of relay 250, the lines 338, 264, and 30!, the switch-arm306 of relay 25!, the line 34!, the coil 340, and the lines 342 and 210to the main line L2. The energizing of the coil 340 causes switch-arms346 and 341 of controller 246 to be closed, closing the reversingcircuit to the armature 24! of motor 10, this circuit being made fromthe rectifier 240 through the lines 348 and 349, the switch arms 346 and341, the lines 350 and 35! and the lines3I-4 and 3I3.

The shaft 8! is now driven in the reverse direction, causing thedirection of movements of the head 32 and carrier '50 to be reversed.The shaft 8! and controller I40 now rotate in a com-- ter-clockwisedirection as viewed from the rear (Fig. 8).

When the button I-82 passes under the nose I of the lever I11, thelimit-switch I19 is closed but nothing happens. When the 'button I48contacts the nose I58 of the lever I56, however, the limit-switch I6! isclosed. This again causes a circuit to be made to the coil 325 of theratchet relay 254 in the manner already described and this coil is againenergized. The switch-arm 265 is; therefore, moved from station No. 2 tostation No. 3 of the relay. This causes the circuit to the coil 335 ofthe relay to be broken, causing the switch-arm 306 todrop out ofengagement, disconnecting the lines and 34!, and causing the switch-arm303 to move into engagement, connecting the lines 302 and 304.

The dropping of the switch-arm 306 out of engagement breaks the circuitto the coil 340 of the controller 246 while the closing of the switcharm303 makes the circuit to the coil 300 of this controller. Thus theoscillating motor 10 is again reversed to cause it again to drive in theforward direction. Again the shaft 8! swings clockwise between the limitset by the stop-buttons I4! and I40 and during this counter-clockwisemovement, the button I82 again trips the lever I11 and the limit-switchI18 without eflecting any operation. At the end of the clockwisemovement, the button I48 again strikes the nose I of the lever I56,again closing the limit-switch I8! and again energizing the coil 325 ofthe ratchet relay 254 to again shift the switch-arm 285.

This time the switch-arm moves from station No. 3 to station No. 4 ofrelay 254. This again causes the coil 335 of relay 25! to be energized,the circuit to this coil being made from the main line Lrthrough thelines 260 and 26!, the limitswitch I80, the line 262, the stop-button251, the line 336, the line 331, the switch-arm 211, the line 338, theline 264, the switch-arm 265. station No. 4 of relay 254, the line 355,the line 338, the coil 335, and the lines 343, 268, and 210 to the lineL2.

The energizing of the coil 335 again closes the switch-arm 306 and opensthe switch-arm 303, causing the oscillating motor 10 to be againreversed as already described. Then the shaft 8! and control member I40move in a counter-clockwise direction and again the button I 82 ridesidly over the nose I15 of the lever I11 and again when Y the button I48strikes the nose of the lever I55, the limit-switch I6! is closed. Thisagain causes the coil 325 to be energized, advancing the switcharm 265'to station No. 5. This breaks the circuit to the coil 335, allowing theswitch-arm 305 of the relay 25! to open and the switch-arm 303 of thisrelay to close.

This again reverses the oscillating motor 10 and shaft 8!. On this swingof the control member I40, however, when the button I82 rides over thenose I15 of the lever I11, closing the limit-switch I19, a circuit ismade to the coil 360 of relay 252. This circuit is from the main line L1through the lines 260 and 26!, the limit-switch I80, the line 262, thestop-button 251, the lines 336 and 331, the switch-arm 211 of relay 250,the lines 338 and 264, theswitch-arm 265 of relay 254, the line 36!,

- the coil 360 of relay 252, the line 362, the nowclosed limit-switchI16, and the lines 363 and the line 210 to the main line L2.

The energizing of the coil 360 of relay 252 causes the switch-arm 283 tobe closed and the switch-arm 284 to be opened. When the switcharm 284 isopened, the circuit to the coil 280 of the controller 235 is broken,stopping the forward rotation of the main motor 65. When the switch arm283 is closed, a circuit is made to the coil 355 of the controller 235,starting the main motor 65 in reverse. The circuit to the coil 365 isfrom the main line L1 through the lines 260 and 26!, the limit-switchI80, the line 262, the stop-button 251, the lines 336 and 331, theswitc'h arm 211 of relay 250, the line 330, the line 264, the line 28!,the switch-arm 283 of relay 252, the line 366, the coil 365, and theline 286 to the main line Le. The energizing of the coil 365 closes-thswitch-arms 310, 31!, and 312, closing the reverse circuit to the motor65 from the main line L1 through the lines 3I0, 361, switch-arm 310 andlines 368 and 284; from the main line La through the lines 218 and 368,switch-arm 31! and lines 313 and 283: and from the line Lc through theline 314, the switch-arm 312, and lines 315 and 285. The main motor 65now drives the gears P and G in reverse.

At the same time that the energized 'coil 360 closes the switch-arm 283and opens the switcharm 284 of relay 252, it closes the switch-arm 328and opens the switch-arm 328 of this relay. This i r puts thelimit-switch ill in the control circuit and cuts out the limit-switchIN. This means that the buttons I48 and I58 (Fig. 8) now con-' trol thelimit of movement oi the controller I48 and of shaft 8!. The shaft 8inow oscillates for the distance determined by the settings of thebuttons its and its. During each swing. the button E82 closes thelimit-switch G18 as before, and, as before, at the end of each swing,one or other of the buttons i188 and-W8 closes the limitswitch ili.

When the limit switch i1!) is closed, a circuit is made to the coil 828of the ratchet relay 288. This circuit is from the main line Li throughthe line 288, the limit-switch ili, the line 888, the now-closedswitch-arm 828 of relay 282. the line 881. the coil 325, and the lines882 and 218 to the main line L2.

This energizes the coil 828 and advances the switch-arm 285 of theratchet relay 288 from station No. 5 of the relay to station No. 6. Thiscauses the cell 385 of relay 256 to be energized, the circuit to thiscoil being made from the main line Ll through the iines 288 and 281,limitswitch 188, the line 282, the stop-button 251, the 0 lines 338 and831, the switch-arm 211 of the relay 288, the lines 888 and 284, theswitch-arm 285, the lines 882 and 339, the coil 335, and the lines 848,269, and 218 to the main line L2. This closes the switch-arm 386 andopens the switcharm 383 of the relay I, reversing the oscillating motor18 in the manner already described.

When the limit-switch MI is closed again at the end of the new reverseswing of control member 148 and shaft 8i. the coil 825 is againenergized to shift the switch-arm 265 of ratchet relay 254 to stationNo. '1. This breaks the circuit to the coil 335 and again reverses theoscillating motor 18 and with it the direction of swing of controlmember 148 and shaft 8I.

When the limit-switch IN is closed once more at the end of the new swingof control member 148 and shaft 8|, the coil 335 is again energizedthrough the connection of station No. 8 of ratchet relay 254 with line338. This again reverses the oscillating motor 18, shaft 8i, and controlmember I48, When the limit-switch I1I is again closed at the end of thisnew swing of shaft 8i and control member I48, the coil325 is againenergized to advance the switch-arm 265 to station No. 9 of the ratchetrelay 254. This again reverses the oscillating motor 18, again causingrerfllzrsal of swing of shaft 81 and control member When the button 182closes the limit-switch 119, on this swing of shaft 8i and controlmember M8, the coil 385 of the relay 253 is energized. The circuit tothis coil is made from the line Ll through the lines 268 and 26I, thelimit-switch N8, the line 262, the stop-button 251, the lines 338 and331, the switch-arm 211 of relay 258, the lines 338 and 264, switch-arm285 of ratchet relay 254, station No. 9 ofrelay 254, the line 386, coil385 of relay 253, the lines 381 and 362, limit- ,swltch I19, and lines363 and 218 to the main line This causes the switch-arm 212 of relay 253to be closed and switch arm 21I of this relay to be opened. The openingof the switch-arm 21I breaks the circuit to the coil 216 of the relay258. This allows the switch-arm 211 of relay 258 to open and theswitch-arm 218 of this relay to close.

When the switch arm 218 is closed, the coil 395 of relay 252 isenergized to reset the switcharms 283, 284, 329, and 328 of this relayto the accesses l6 positions shown in Fig. 18. The circuit to the coil885 is made from the main line L1 through the lines 268 and 26I, thelimit-switch I88, the line 262, the stop-button 251, the line 238, theswitch arm 218 of relay 258, the line 38I, the switch-arm 212 of relay253, the line 386, the coil 385, and the lines 381, 269 and 218 to themain line In.

The closing of the switch arms 212 and 218 also makes a circuit to thecoil 888 of ratchet relay 268. This circuit is from the main line inthrough the lines 268 and 26B, the limit-switch 188, the line 262, thestop-button 251, the line 88, the switch-arm 218, the line 881, theswitcha-rm 212, the line 892, the coil 888, and the lines 382 and 218 tothe main line L1. When the coil 888 is thus energized, the switch-arm285 is reset from station No.-9 back to station No. l.

When the switch-arm 811 of the relay 288 is opened, the hold-in circuitto the coil 288 of controller 235 is broken, and the circuits to thecoils 888 and 388 of controller 288 are also opened. Hence, the maindrive motor and the oscillating motor 18 are stopped, stopping themachine. The operation of lapping the pair of gears is complete, and thegears may be removed from the machine and a new pair chucked thereon. Torestart the machine, it is again necessary to press in the start-button256.

It is to be noted regarding the above-described circuit that, if thepower should fail and the machine stop before the lapping operatlon iscompleted, the switch-arm 265 of ratchet relay 254 will not be reset.When the machine is started formed will not be repeated, but theswitch-arm 265 will simply remain at whatever station it hasreached-when the power is cut off, and when the power is restored again,the machine will resume its operations from the point where it wasstopped. The switch-arm 256 can only be reset when it has reached No. 9station of the ratchet relay 254, that is, when it has reached theposition where the lapping operations on the pair of gears have beencompleted.

As already stated, if one of the stop-buttons 181, I48, 149. or I58should fail for any reason to trip the limit switch i6I or ill toreverse the direction of swing of shaft 8i, then the button 113 or l14will open the normally-closed limitswitch 188. This will break thecircuits to the motors 65 and 18 and stop the machine.

In order to obtain the'desired tooth hearing or contact on oppositesides' of the teeth of a pair of spiral bevel or hypoid gears, it hasbeen demonstrated that it is desirable to run the meshing gears togetherfirst in one direction and then in the other and that during rotation inopposite directions, the gears should be moved through different anglesand at different rates. The adjustable stops MI, I42, I43, and I44 allowmoving the gears through different angles. The different rates areobtained by adjustment of the rheostats 236 and 231 which control theshunt field and armature voltages of the motor 18 and hence its speed ofrotation during forward and reverse drives, respectively. The tworheostats are connected together through the lines 488 and MN. The lines488 and 48I serve, also, to connect the two rheostats to the rectifier248. The two rheostats are connected to the rectifier 238 through thelines 482 and 483. The rheostat 236 is connected to the line 285 by theline 484, while the rheostat 231 is connected to the line 386 by theline 485. Thus, the rheostat 236 is wired to control the speed of themotor 18 during forward rotation of the gears being lapped underactuation of motor 65, while the rheostat 251 is wired to control thespeed, of the motor I during the re-.

verse rotation ,of the gears.

As already stated, the load on the gears during lapping may be varied byadjustment of the of course, that during operation of the machine,

a suitable lapping compound is applied to the gears by means known inthe art. After the various adjustments have been made to bring the gearsto be lapped into meshing engagement; the several rheostats have beenset to control the speed of the oscillating motor-during forward andreverse rotation of the gears and to control the load on the gears; thestops I 4|, I42, I45, and I44 have been adjusted to control the anglethrough which the control member I40, shaft 8| and cam 85 are oscillatedduring forward and reverse rotation of the gears; and the blocks IIII(Fig. 3), I23 and I24 (Fig. 4) have been adjusted to determine theamounts of axial and oscillatory movements of carrier 50 and spindle 51for the up and down movement of head 52; the operator starts the machineby pressing in start button 256. Then the gears are driven in mesh bymotor 65 and the head 32 is moved up and down, and the carrier 50ismoved back and forth and swung from side to side through operation ofthe motor III. The cam shaft 8| is rotated. by motor III in onedirection until one of the buttons I41 or I48 strikes the lever I56 toclose the limit-switch I6I. Then the motor I is reversed, and head 32and carrier 50 are moved in the opposite direction. Two complete forwardand reverse swings of the cam shaft III, that is, two complete up anddown movements of the head 32, oscillations of carrier '50, andreciprocations of carrier 50 are effected. Then, when the switch-arm 265of relay 254 reaches station No. 5 of that relay, the limit-switch IBIis rendered ineffective and the limit-switch III is made effective. Thenthe motor 55 is reversed, reversing the direction of rotation of thegears being lapped. Then the shaft 8| is swung back and forth throughthe distance determined by stops I49 and I50. Two full up-and-downmovements of the head 32, two full oscillations and two fullreciprocations of the carrier 51 are made. Then the switch-arm 265reaches station No. 9 of the ratchet relay 254, and the lapping iscompleted.

Figs. 12 to 17 inclusive illustrate diagrammatically the motions of themachine in the lapping of a pair of spiral bevel or hypoid gears P andG. The gears shown are of left-hand spiral curvature, and they areconstructed to have the usual amount of tooth surface mismatch orlocalization of tooth bearing, the side surfaces 4" and 8 of a toothspace of the gear contacting at a central area along the sides with themating side surfaces 9 and 420, respectively, of a tooth of the pinion.

Figs. 12 and 13 show the gear G and pinion P in mesh in correct runningposition with their aplces H5 and 41-6 coinciding. As the carrier 50moves rectilinearly in one direction, moving the piniontoward the largeend or heel of the gear teeth, the head 52 is simultaneously moveddow'n,and the carrier 50 is swung outwardly. Thus, as shown in Figs. 14 and15, the apex 4|! of the pinion is displaced downwardly and outwardlyfrom the apex 4| 5 of the gear, and simultaneously the pinion iswithdrawn axially to prevent interference between the gear and-pinionteeth and to maintain the backlash constant. When the carrier 50 movesrectilinearly in the opposite direction, the head 32 is simultaneouslymoved up. and the carrier 56 swung first inwardly and then outwardlyagain. Thus, the pinion moves through the position shown in Figs. 12 and13 to the position shown in Figs. 16 and 17. In this last position, theapex 4I5 of the pinion is displaced upwardly and inwardly with referenceto the apex 5 of the gear. Thus, the tooth surfaces of gear and pinionslide over one another and eflfect the lapping operation.

While the invention has been described particularly with reference to amachine for lapping gears, it will be understood that essentially thesame structure may be used in a machine for burnishing gears, as will beobvious from the art. It will further be understood that, while theinvention has been described in connection with a machine for finishinggears, certain features are capable of general application. Thisapplication is intended to cover any variations, uses, or adaptations ofthe invention following, in general, the

principles of the invention and including such departures from thepresent disclosure as come within known or customary practice in the artto which the invention pertains and as may be applied to the essentialfeatures hereinbefore set forth and as fall within the scope of theinvention or the limits of the appended claims.

Having thus described our invention, what we claim is:

1. In a machine for finishing tapered gears. a pair of rotatablespindleswhose axes are angularly disposed to one another, means fordetachably securing a gear to each of said spindles. means for adjustingthe gears into mesh, means for driving one of the spindles to drive theother spindle by the meshing engagement of the gears, means forreciprocating the drive spindle axially to move the gear carried therebylengthwise of the teeth of the other gear, and means for reciprocatingone of said spindles in time with the first named reciprocating movementina direction at right angles to the axis of the drive spindle to'efiectrelative movement between the gears in a direction transverse of theirteeth.

2. In a machine for finishing tapered gears, a pair of rotatablespindles whose axes are angularly disposed to one another, means fordetach,- ably securing a gear to each of said spindles, means foradjusting the gears into mesh, means for driving one of the spindles todrive the other spindle by the meshing engagement of the gears.

- means for reciprocating the drive spindle axially 19. a said gears astheir teeth move longitudinally and transversely of one another.

3. In a machine for finishing tapered gears, means for supporting apair. of gears .to run together in mesh with angularly disposed axes,means for rotating one of the gears to eflect rotation of the pairthrough their intermeshing' engagement, means for effecting rela'tivemove ment between the gears in a direction lengthwise of their teethduring their rotation, means for simultaneously eiiecting relativemovement be-.

tween the gears transversely of their teeth, and means for adjusting oneof said two last named means to adjust the amount of one of saidmovements independently of the other.

4. In a machine for finishing tapered gears, means for supporting a pairof gears to run together in mesh with angularly disposed axes, means forrotating the gears together, means for efiecting relative movementbetween the gears lengthwise of their teeth during their rotation, meansfor simultaneously eifecting relative movement between the gearstransversely of their teeth, means for simultaneously eifecting relativemovement between the gears in the direction of tooth depth, and meansfor adjusting at least two of the last three named means .to adjust theamounts of said relative movements with respect to one another.

5. In a machine for finishing tapered gears, means for supporting a pairof gears to run together in mesh with angularly disposed axes, means forrotating one of the gears to eifect rotation of the pair through theirintermeshing engagement, said gears being mounted for relative movementslengthwise, transversely, and depthwise of their teeth, means foreffecting one of said movements, and means. operable on said movement toeffect simultaneously and in time -therewith the other two movements,said last named means being adjustable to vary the ratio of the threemovements relative to one another.

6. In a machine for finishing tapered gears, means for supporting a pairof gears to run together ,in mesh, means for rotating the gears first inone direction and then in the other, means for eifecting a plurality ofreciprocaitory movements between the gears lengthwise of their teeth anda plurality of reciprocatory movements transversely of their teethduring rotation of the gears in each direction, and means for adjustingthe amount and speed of the reciprocatory movements during rotation ofthe gears in on. direction independently of the amount and speed of thereciprocating movement during rotation of the gears in the oppositedirection.

7. In a machine for finishing gears, a pair of spindles for supporting apair of gears to run together in mesh, means for rotating the spindlesfirst in one direction and then in the other, a support in which one ofthe spindles is journaled, a cam, a follower engaging said cam andsecured to said support, means for oscillating the cam to efifectreciprocation of the support during rotation of the-spindles, adjustablemeans for limiting the amount of oscillation of the cam during rotationof the spindles in the forward direction, and separately adjustablemeans for limiting the angle of oscillation of the cam durin rotation ofthe spindles in the reverse direction.

8. In a machine for finishing gears, a pair of spindles for supporting apair of gears to run together in mesh, means for rotating the spindlesfirst in one direction and then in the other, a support in which one ofthe spindles is journaled.

dles in both the forward and reverse directions.

an oscillatory cam for reciprocating said support, means for oscillatingsaid cam, means for reversing the direction of rotation of the spindiesafter a predetermined number of oscillations of the cam, and separatemeans for determining the rates of oscillation and angles through whichthe cam is oscillated during rotation of the spin- 9. In a machine forfinishing gears, a support,

a head reciprocally mounted on the support, a

carrier movably mounted in the head, a spindle journaled in .thecarrier, a second spindle journaled in the support, said spindles beingadapted to carry a pair of gears, an oscillatory cam for reciprocatingthe head, means for oscillating the cam, and a block and follower, oneof which is secured to the carrier and the other to the support, saidblock having a guide'surface on which the follower rides during movementof the head to impart movement to the carrier on movement of the head,said block being adjustable angularly to incline its guide surface tothe direction of reciprocation of the head.

10. In a machine for finishing gears, a pair of spindles-means forsecuring a gear to each of the spindles, a support, a head reciprocallymounted on the support, a carrier in which one of the spindles isjournaled, said carrier being' mounted on the head for oscillation aboutan axis parallel to the axis of said spindle and for reciprocation inthe direction of said axis, means for reciprocating the head, twocontrol devices each of which comprises a block and follower, one ofwhich is secured to the carrier and the other of which is secured to thesupport, each of the blocks having a straight guide surface on which thefollower rides during reciprocation of the head, one of the blocks beingadjustable about an axis extending in the direction of the axis ofoscillation of the carrier and the other of the blocks being adjustableabout an axis extending at right angles to the axis of oscillation ofthe carrier, and means for rotating the spindles first in one directionand then in the other.

11. In a machine for finishing tapered gears, a pair of spindles thatare angularly disposed to one another, means for detachably securing agear to each of said spindles, means for adjusting the spindles relativeto one another to bring the gears into mesh, means for rotating thespindles first in one direction and then in the other to rotate thegears in mesh, an oscillatory cam for eifecting relative reciprocatorymovements between the gears while they are rotating, separatelyadjustable means for controlling the angle through which the cam isoscillated and the speed at which it is oscillated during rotation ofthe spindles in the opposite directions, and means actuated by saidreciprocatory movements for eflecting further relative reciprocatorymovements between the gears in a direction inclined to the first namedreciprocatory movements.

, 12. In a machine tool, a rotary spindle, an electric motor for drivingsaid spindle in both directions, separately adjustable means forcontrolling the speed of rotation of the motor during forward andreverse rotations of the spindle, respectively, an oscillatory controlmember, and means

